1. Field of the Invention
The present invention relates to a substrate detecting apparatus and method for detecting a substrate, a substrate transporting apparatus and method for transporting the substrate, and a substrate processing apparatus and method for processing the substrate.
2. Description of the Background Art
A substrate processing apparatus is used for subjecting a substrate such as a semiconductor wafer, a glass substrate for liquid crystal display, a glass substrate for photomask, and a glass substrate for optical disc to a variety of processings. In the fabrication process of a semiconductor device, for example, a substrate processing apparatus is used in which each of a series of processings is unitized for improved productivity, and the plurality of processing units are integrated.
In the substrate processing apparatus, one substrate is, in general, successively subjected to a plurality of different processings. Accordingly, a substrate transport robot for transporting a substrate from one unit to another is provided.
FIG. 23 is a perspective view showing an example of the conventional substrate processing apparatus 500 (refer to, for example, JP 2001-82653 A).
The substrate processing apparatus 500 shown in FIG. 23 performs a series of processings, such as coating processing, developing processing, heat processing, and cooling processing. The apparatus has a processing region A at the bottom side of the paper of FIG. 23; a processing region B at the top side; and a transport region C between the processing regions A and B.
In the processing region A, a spin coating unit (spin coater) SC for coating a substrate W with a processing liquid, and a spin developing unit (spin developer) SD for performing developing processing to the substrate W are arranged. In the processing region B, a heating unit (hotplate) HP for performing heat processing to the substrate W, and a cooling unit (cooling plate) for performing cooling processing to the substrate W are arranged. A substrate transport robot 60 is movably provided in the transport region C. Further, an indexer ID for substrate loading and unloading is arranged at one ends of the processing regions A, B.
The indexer ID is provided with an indexer robot 51 for transferring the substrates W between a plurality of cassettes 1 which store the substrates Wand the substrate transport robot 60 provided in the transport region C. The transfer of substrates W between the substrate transport robot 60 and indexer robot 51 takes place in a transfer portion TP.
In other words, while moving in the direction of arrow U, the indexer robot 51 of the indexer ID takes out a substrate W from a cassette 1 to transfer it to the substrate transport robot 60 in the transfer portion TP, and reversely receives a substrate W which has undergone the series of processings from the substrate transport robot 60 in the transfer portion TP to return it to a cassette 1.
The substrate transport robot 60 has a transport arm 61, and transports the substrate W transferred from the indexer robot 51 to a designated processing unit or transports the substrate W received from one processing unit to another or to the indexer robot 51.
In the conventional substrate transport apparatus 500, the substrate W can thus undergo the series of processings while being transported to each of the processing units by the substrate transport robot 60 and the indexer robot 51.
In recent years, however, each of the processing units and the substrate transport apparatus are increasing in size with a trend in upsizing a substrate. The upsizing of a substrate has led to an increase in the production cost per substrate, and potential dropping or breakage of a substrate caused by poor transportation may result in increasing the cost.
In the conventional substrate transport apparatus 500, for example, if the substrate W is placed on the transport arm without being supported by some of a plurality of support pins provided on the transport arm, the substrate W will be inserted into each of the processing units while being in an inclined attitude. In this case, the substrate is held improperly in each of the processing units, which causes part of the substrate W left unprocessed, or breakage in the substrate W.
For this reason, optical sensors are used for the detection of positional deviation of the substrate W. However, in some cases where translucent materials such as glass are used for the substrates W, it is difficult to accurately determine the attitudes of a variety of substrates W using such optical sensors.